The present invention relates, in general, to grinding and polishing machines, and in particular, to a new and useful apparatus which is specifically suited to the grinding and/or polishing of the gasket grooves in a cover plate header box.
FIG. 1 illustrates a conventional header box 10 which includes a U-shaped box portion 12 having sides connected to a pair of outwardly extending flanges 14. Each flange contains a row of bolt holes 16 and a gasket groove 18 designed to receive a gasket (not shown). Bolt holes 16 are used to accommodate bolts that squeeze a cover against the flanges 14 thereby forming a pressure seal at the gasket.
A milling or other cutting tool is used to form the gasket grooves 18. Due to the dimensions of the header box, the grooves for confining the gasket are manufactured with machine lines across the pressure boundary. These are shown at 20 in FIG. 2. These machine lines are a serious detriment to the pressure seal since they extend across the pressure gradient, between the high pressure region and the low pressure region to be separated by the header box. It is thus necessary to grind away and polish the gasket grooves 18, to eliminate the machine lines and any other imperfections in the surfaces of the groove.
It is known to use hand-held grinders for this purpose but this is time consuming and inaccurate. It produces wavy surfaces in the groove which also diminish the pressure seal. It is also not practical to machine the grooves in a different way. Currently, they are machined with mill cutters which leave the machine lines.